Wall Street's game of musical chairs

Wall Street has been playing a game of musical chairs, and the tempo is picking up.

From UBS to Deutsche Bank to JPMorgan Chase to Citigroup, executives are hopping to rival banks at a rapid clip. With low trading volume and tough market conditions, many chairs are also vanishing when the music stops.

Among the lost chairs so far: Mitch Moore, the global head of UBS's (UBS) prime brokerage unit, resigned last Friday. Moore ran the division of the bank that executes and clears trades for hedge fund clients.

UBS has had a revolving cast of characters leading that unit recently with four new heads in the past three years.

Now UBS is shaking up the division in a major way by moving the head of the bank's derivatives trading, Jason Barron, into a role that oversees both global derivatives and prime brokerage, a UBS spokesperson confirmed. Meanwhile, the bank recruited Roger Naylor from Deutsche Bank (DB) to run its equity derivatives trading operations.

Deutsche Bank had recently lured Brad Kurtzman away from Citigroup (C) to run its derivatives unit. Kurtzman, a former trader with Citadel, won't join Deutsche Bank until July.

UBS isn't the only firm that's shaken up its prime brokerage business recently. JPMorgan's (JPM) head of prime brokerage Lou Lebedin left that role a few weeks ago.

All over Wall Street, the prime brokerage business has been fraught with challenges. New regulations for hedge funds and banks makes it more expensive for large banks to provide these services to hedge funds. Yet banks have been hungry for these clients, so they've been undercutting one another on price, thinning out profit margins in these units.

Maureen Farrell is a staff writer at CNNMoney and covers Wall Street, banking, mergers and the stock and bond markets. Prior to joining CNNMoney, she covered venture capital and entrepreneurs for Forbes, and mergers and bankruptcy for Mergermarket and Debtwire, both divisions of the Financial Times.